This invention relates generally to connectors for routing signals between printed circuit boards. More specifically, this invention relates to high density connectors that provide high speed signals in a low noise, impedance controlled manner.
Electrical connectors are widely used in modern electronic equipment. Sometimes, multiple printed circuit boards are connected together in a perpendicular fashion through a “backplane” or “motherboard”. For example, many computers are assembled in this fashion. The connectors are typically made in one piece or two piece configurations, are connected to the printed circuit boards through tail portions, and are easy to mate/unmate. The connectors make the assembly and maintenance of the electronic equipment easier. The circuit cards plugged into the backplane or motherboard are called “daughter cards”.
In other instances, circuit boards are connected together other than through a backplane. For example, circuit boards may be connected together in a parallel manner. When two circuit boards are connected in this fashion by a connector, such a connector is generally referred to as a “mezzanine” connector. Two circuit boards can also be connected edge-to-edge in a “docking” fashion. Connectors like those used on a backplane can be used in all of these case. The shape of tail portions of the connector contacts might be different to facilitate different mounting positions of the circuit boards. However, because similar connectors can be used, the term “backplane connector” can refer to either connectors in a backplane system or connectors used in other systems.
One-piece “card edge” connectors have plastic housings with rows of conductive contacts along either side of a slot down the middle. The daughter card has plated contact pads along one edge. That edge of the daughter card is plugged into the card edge connector. The conductive contacts are spring biased against the contact pads on the daughter card, completing conductive paths between the two circuit boards.
With two-piece connectors, an insulative housing is mounted on each circuit board to be connected. Each housing has numerous conductive contacts in it. When the two housings are mated, the conductive contacts in each housing touch, making electrical contact. Usually, some sort of spring force is used to keep the contacts together. Many connectors of this type have one set of contacts shaped as pins with the other set of contacts shaped as receptacles into which the pins can be inserted.
A refinement on the two-piece connector has been the use of ground plates in the insulative housing to enhance electrical characteristics. Examples of such connectors are found in U.S. Pat. Nos. 4,571,014, 4,846,727, 4,898,546, 4,975,084, 5,055,069, 5,135,405, 5,403,206 and 6,042,386. Each and every one of these references are incorporated herein.
While there are many types of connectors available, the inventors of the present invention have not observed a small, low profile two-piece connector capable of providing data transmission speeds from 2.5 GHz up to, in certain instances, 10 GHz in a low noise, impedance controlled manner.